The present invention relates to the deployment of electronic circuitry and components in hostile environments, most particularly in the bores of oil and gas wells. While electronic circuitry and components which can survive the temperature extremes encountered in well bores and which have a sufficiently low power draw to permit the use of battery power are known in the art, a recurring problem encountered by designers of downhole tools including instruments incorporating such circuits and components is the isolation of same from the shock and vibration encountered as a matter of course during the trips into and out of well bores, as well as that generated by streams of flowing gas and oil, and the deployment and operation of other tools, such as perforating guns, in the well bore. While attempts have been made to solve such problems, there is a present lack of a packaging arrangement for downhole instruments which will provide substantial shock and vibration isolation as well as protection from damage resulting from normal handling during testing, maintenance and repair of the instruments, while affording easy access to the circuitry and components and rapid, reliable electrical connection and disconnection between a series of instrument-containing tools in the same string.